Tuesday 1 February 2011 07.33 EST
First published on Tuesday 1 February 2011 07.33 EST

Boris Johnson's popular bike-hire scheme is to be extended to the east of London by spring 2012, it was announced today, as figures show the blue bicycles have clocked up 10 million kilometres in the first six months of their operation in central London – the equivalent of riding to the moon and back 13 times.

Tfl says the "spring deadline" to extend to the east in readiness for the 2012 Olympic Games is likely to fall in March or April, by which time the scheme will cover 65 square kilometres of the capital with 8,000 hire bikes available from 14,400 docking points.

Data published to mark the first six months of the mayor's cyclehire scheme shows users have made 2.5 million journeys using the bikes, 95% of which have been under half an hour long – which means the vast majority of people using the scheme are not paying any more in access fees than the £1 for 24 hours, £5 for seven days or £45 for a year.

So far, eight of the bikes have been stolen – although two have since been recovered – in contrast to the similar vélib' scheme in Paris that saw 3,000 bikes stolen within the first 12 months of its launch.

The scheme currently operates in Camden, City of London, Hackney, Islington, Lambeth, Kensington and Chelsea, Southwark, Tower Hamlets, Westminster and several of the royal parks.

On its busiest day of operation, more than 27,500 journeys were made using the cycle hire covering more than 124,800km. Nearly 110,000 people are now members; casual customers have made 70,000 journeys since the scheme was opened to them two months ago.

Boosted by the popularity of the scheme, launched last July, Johnson had signalled his intention to spread the scheme across a larger area of east London in time for the 2012 Olympics.

Ranger told a conference entitled Cycling: The Next Urban Challenge that the blue bikes had made a "huge contribution" to the cycle revolution Johnson wants to bring to the capital.

Cycling currently accounts for 2% of journeys in the capital.

Ranger said: "One of the best things about Barclays Cycle Hire has been the number of cyclists who have told me how the bikes have made a positive change to their life, as well as their commute. Users say they feel healthier, fitter and invigorated when they reach their destination."

Currently, there are approximately 5,000 bikes in central London at 368 docking stations, but TfL insist the full complement of 6,000 bikes and 400 docking stations originally promised for the first phase will be in place by March this year.

TfL urged bike-hire users to ensure a green light switches on when they dock the bike at the end of a journey to ensure it has been locked in properly. Failure to do so is believed to have contributed to some of the thefts.

The disappearance of a bike means a £300 charge will disappear from the user's credit card, though Tfl told the Guardian that the disappearances to date have been looked at on a case-by-case basis.